I can confirm what Straubm noticed when I was using kicad-6.0.9 for the first time.
In fact I built kicad-6.0.8 (from scratch) and was working for almost 3 days constantly
to acquantain myself (I come from kicad-5.99 and hence upgraded to kicad-6.0.8).
I was told that kicad-6.0.9 was lying around the corner so I decided to upgrade from
The phenomenon will show up when the schematic has been checked on violation
errors (which as result is described in issue 12814), when going to the
pcb design. The message popped up describing what Straubm was seeing.
I tried to return to kicad-6.0.8 in order to use the same project but unfortunately I
got the same result and the damage could not be undone.
I really had to restore my project backup (built with kicad-5.99) and tried again with
kicad-6.0.8 to see if the project was messed up again. Fortunately no violation errors
were detected after making some improvements with kicad-6.0.8. While at kicad-6.0.8
I started up the pcb design and that went OK as well. I also checked that another
project is doing OK again with kicad-6.0.8 (both schematic diagram and pcb design).
Then again started up kicad-6.0.9 with the first project. What ever I tried to do to
reproduce the phenomenon and damage it did not show up even switching twice from
kicad-6.0.9 to kicad-6.0.8 and back.
I could not reproduce the phenomenon and the damage afterwards.
I suspect that there are some leftovers in the kicad-6.0.8 project itself which were
introduced after a lot of work and/or improvements in the project. But A very
weird experience …